In response to the diminishing availability of petroleum based liquid fuels, such as gasoline, diesel fuel, jet fuel, etc., as well as for other reasons, liquefied fuel gasses, such as LNG, have seen increased use as alternative fuels for combustion engines. Simultaneously, combustion engines have been developed, and are currently being developed, which can efficiently utilize these alternative fuels. As such, the manufacturers and users of locomotives, over-the-road trucks, off-the-road trucks, boats, etc., as well as others, are continuously investigating combustion engines that efficiently utilize liquefied fuel gas as a combustion fuel.
These types of liquefied fuel gas combustion engines often operate in environments that can change dramatically within a relatively short period of time, particularly if such engines are used in mobile applications. For example, during a single trip between destinations, a locomotive can operate in an open environment and, at select times during the trip, in a closed environment (such as in a tunnel). When the locomotive operates in an open environment, it is generally provided with an adequate amount of relatively cool ambient air that may be used for both combustion and for cooling the combustion engine, as well as other heat-sensitive components, such as electronics, of the locomotive. However, when the locomotive operates in a more closed environment, such as a tunnel, the amount of available air useful for cooling purposes may be considerably reduced. Further, since the temperature of that air can be considerably higher than standard ambient air, the thermal capacity of that air for cooling purposes can be decreased significantly over “standard” ambient air. For this reason, in such closed environments, performance of a mobile machine, such as a locomotive, can be severely affected. Examples of issues that can arise include overheating of the engine and/or related electronics and/or other heat-sensitive equipment. Alternatively, a mobile machine may have to be de-rated from its actual “standard” operating capabilities in order to account for the diminished capabilities of that machine in the closed environments that may only account for a very small amount of actual operating time of that locomotive.
One attempt to improve cooling of a mobile machine having a combustion engine utilizing a liquefied fuel gas is described in U.S. Pat. No. 5,375,580 (“the '580 patent”) of Stolz et al. that issued on Dec. 27, 1994. The '580 patent describes a combustion engine that is either supercharged or turbocharged, potentially in stages. Specifically, the '580 patent discusses the use of a liquefied fuel gas in an internal combustion engine to which compressed intake combustion air is supplied using, for example, a supercharger or turbocharger, and which is fueled with a liquefied fuel gas, such as, for example, liquefied natural gas (LNG), wherein the cold revaporized fuel gas is heat exchanged with the compressed intake combustion air to cool the compressed intake combustion air to improve efficiency and performance of the engine. This heat interchange between the heated intake air and the cold liquefied fuel gas warms the liquefied fuel gas from its cold state to a temperature that permits operation of the internal combustion engine and, simultaneously, cools the compressed intake air to a temperature that improves engine efficiency. However, the cooling system disclosed in the '580 patent is not necessarily useful in all situations, and particularly, situations such as those described herein wherein additional supplemental cooling is necessary due to the combustion engine utilizing a liquefied fuel gas being subject to temporary abnormal operating conditions.
Specifically, the cooling system described in the '580 patent is related to a cooling system for a combustion air charging system or after cooler for a turbocharger or supercharger. It does not deal with direct engine cooling, supplemental cooling, or cooling of heat-sensitive components such as electronics. Furthermore, the cooling system described in the '580 patent does not deal with specific instances of operation of the combustion engine wherein the standard operating conditions for the combustion engine, that the engine is generally rated for, change, due to, for example, the combustion engine travelling through a tunnel. As such, the cooling system described in the '580 patent may not be used to provide supplemental, although needed, cooling to cool the engine of a combustion engine when it encounters unusual ambient air conditions, such as when the combustion engine is being utilized in a locomotive travelling through a tunnel Finally, since the cooling system described in the '580 patent describes a system for cooling the air either entering a supercharger or turbocharger, between stages thereof, or as an aftercooler prior to the air entering the combustion chamber of the internal combustion engine, it does not disclose a method or an apparatus for use of the cooling capacity of a liquefied fuel gas to the components of the engine itself, or of other heat-sensitive components, much less to provide supplemental cooling when the combustion engine is being subjected to unusual or temporary ambient operating conditions.